The invention relates to a method and apparatus for controlling the flashing operation of an electronic flash system and more particularly relates to a method and apparatus for improving the efficiency of the voltage converter which powers the electronic flash.
Electronic flash devices are known in the art in which a single flash tube of the device is utilized to take a plurality of flash pictures. Prior to the taking of each picture, a battery-powered circuit charges a storage capacitor to a relatively high voltage level for driving the flash tube upon the photographer closing the camera switch.
During the flash, the voltage on the storage capacitor is drained until there is insufficient voltage across the capacitor to maintain the flash tube in conduction or until the flash is purposely terminated by an automatic control circuit. After the flash has been terminated, the storage capacitor is recharged in preparation for taking the next picture.
A voltage converter circuit which charges the capacitor is powered by a battery which permits a certain number of flashes to be performed in accordance with the life of the battery. Thus, a method and apparatus for increasing the number of flashes permitted with a single battery charge would be highly welcomed.
Further, it would be desirable to increase the voltage converter efficiency in not only automatic flash termination systems in which the flash duration is automatically controlled, but also in non-automatic flash systems in which the flash is terminated due to voltage drain on the flash capacitor. Also, it would be desirable to maintain an adequate light output from the flash as the capacitor's charged voltage level decreases during battery life.